1887

Abstract

The production of many virulence factors by is regulated by the quorum-sensing (QS) response. In this regulatory network LasR and RhlR, bound to their corresponding autoinducers, play a central role. The QS response has a hierarchical structure: LasR/3O-C12-HSL activates the transcription of , and RhlR/C4-HSL activates the transcription of several genes, including the operon, which encodes the enzymes responsible for rhamnolipid synthesis. The operon is located immediately upstream of the gene. has four transcription start sites, two of which are located in the coding region. Vfr directly activates transcription of , and has been reported to be also involved in expression. The aim of this work was to characterize the details of the mechanism of transcriptional regulation. We show that Vfr directly regulates transcription through its binding to several Vfr-binding sites (VBSs) present in the promoter region, one of which has a negative effect on transcription. Two of the VBSs overlap with boxes where LasR/3O-C12-HSL binds to activate transcription. We also show that transcription is subject to positive-feedback autoregulation through RhlR/C4-HSL activation of the promoter. This positive autoregulation plays a major role in expression.

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2011-09-01
2019-10-22
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vol. , part 9, pp. 2545 - 2555

Oligonucleotides used for construction of fusions, mutants and RT-PCR [PDF](373 kb)



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